This invention relates to towed bodies and more particularly to a recovery mechanism for recovering the towed body for reuse.
As will be appreciated, aerial towed objects are used for a variety of purposes, including decoys, testing, and scientific investigations. In one embodiment the decoys are used to draw various types of guided weapons away from an aircraft that the weapons are intended to destroy. As will be appreciated, these towed targets and decoys contain various types of electronic circuits to create an apparent target to a weapon to attract the weapon to the decoy rather than the aircraft. One such active electronic device is a amplifier wave tube transponder to which high voltages must be applied to power the traveling wave tube. Additionally, other controls for the traveling wave tube or other electronics in the towed object are transmitted in one embodiment along a fiber-optic transmission line, which is both fragile and frangible.
The typical manner of deployment is such that when the decoy has fulfilled its function, it is simply cut loose. In this case, the fiber optic wires and the high tension line are severed, with the severing taking place after the high voltage has been removed and after all usable signals along the fiber optic cable have been terminated.
The practice of cutting loose decoys after use and using them as an expendable commodity causes a number of problems. As a result it becomes important to be able to recover the towed vehicle itself, mainly because of the cost of the towed vehicle, as well as the fact that replacing towed vehicles often is difficult due to the long lead times for the manufacture and provision of such decoys.
For instance, typically a towed counter-measure decoy may cost as much as $50,000 per decoy round. As many as eight decoys per sortie or mission can be deployed and as such, assuming 400 sorties per month, then the total expense of deploying expendable decoys is quite large, making the cost for the protection of the aircraft that employs these decoys excessive. Moreover, in a wartime setting the decoy cannot be manufactured quickly enough. So bad is the situation that it may be necessary to scrounge used decoys from the battlefield where they fall.
It will be appreciated that prior to the subject invention, the only type of retrievable devices from aircraft were the sonobuoys that were dropped from helicopters on a line and then winched back up into the helicopter itself. Another type of towed device is an air speed head that is used to measure a variety of parameters behind an airplane. These types of devices were winched back into a pod on the aircraft in a conventional manner.
It will be appreciated that in the above examples of winched-in sonobuoys or towed instruments, the instruments were never meant to be disposable and were never used, for instance, in any kind of airborne counter-measure environment. Thus they were not carried in such a manner that they could be rapidly deployed in a battlefield scenario.
Previous embodiments of the above airborne-winch systems are incompatible with deployment of towed decoys and current volume constraints on tactical aircraft, both due to size and due to problems with slowly winching out a drogue or towed vehicle of any kind. Note that sonobuoys and pod-mounted countermeasures typically were carried in an equipment pod the size of the MK-84 aerial bomb or the ALQ164-type electronics counter-measures pod. What will be appreciated is that these pods are exceptionally large and preclude, for instance, the carrying of armaments in the position where a pod is located. Thus the payload of any attack aircraft is severely limited when using such unwieldy winching systems along with associated housings which are many times the size of the normal decoy round.
There is therefore a need for a compact launching and retrieval system for decoy rounds with an improved and miniaturized winching mechanism that would permit both rapid deployment of the decoy while at the same time being able to reel in the decoy and permitting it to dock so that it can be recovered.
By way of further background, the types of decoys involved have included devices which counter-measure infrared guided and radar guided missiles that pose the primary threats to military aircraft engaged in a combat environment. It will be appreciated that these missiles use their radar guidance systems to get within striking distance of the aircraft, thereby substantially increasing their probability that the IR system on the missile will be able to lock onto the target.
Current military aircraft are particularly vulnerable to attack from IR-guided surface-to-air and air-to-air missiles. Statistical data of aircraft losses in hostile actions since 1980 show that almost 90 percent of these losses have been the result of IR-guided missile attacks. As a result, the ability to deploy and then recover decoys that can counter-measure the IR guidance systems on these missiles is of great value to protect aircraft during combat situations. As mentioned above, the IR-guided system initially utilizes radar guidance and then switches over to IR guidance as they come into closer proximity to the target. If one can counter-measure the radar system, then the IR portion can never lock onto the particular infrared target. To do this, the missile is deflected away by generating a signal that causes the radar guidance system in the missile to think that the target is actually elsewhere than it actually is.
In the past, the ALE-50 Towed Decoy system currently in the inventory of the US Armed Forces includes a decoy round in a canister and a reel payout mechanism. When the decoy has served its purpose, it is cut loose and the ALE-50 decoy is lost.
Moreover, the same scenario is true for the more modern ALE-55, or in fact, any type of expendable towed vehicle.
In summary, prior art decoys were intended to be sacrificed and the towline was typically cut at the aircraft at the end of flight or mission. Thus, these systems did not contemplate the winching in or reeling in of the decoy. The reason is because these decoys needed to be rapidly deployed. One rapid deployment method included a spindle that paid out the towline in much the same way as a spinning reel pays out fishing line. Although spinning reel-like techniques have existed for fishing, in the area of rapidly deployed decoys they were not used to winch decoys. Also, the spindles themselves were not necessarily driven.
As will be appreciated, there are a number of U.S. patents that in general cover towed vehicle deployment, such as U.S. Pat. Nos. 5,836,535; 5,603,470; 5,605,306; 5,570,854; 5,501,411; 5,333,814; 5,094,405; 5,102,063; 5,136,295; 4,808,999; 4,978,086; 5,029,773; 5,020,742; 3,987,746 and 5,014,997, all incorporated by reference herein. In none of these patents is the subject retrievable system shown or taught.
In the subject system, a device is deployed that captures the towline and reels it in to the canister so that as the towline is brought in, the deployed decoy is reeled in, and is secured to a cradle or saddle which telescopes out from the canister during the retrieval process. The decoy is captured by the cradle due to the tug of the tow line around sheaves or other like devices such that the decoy is taken up and is held to the cradle from whence it can be removed when the aircraft returns to base.
The result is that the decoy is not lost or sacrificed but is rather brought back for reuse or refurbishment, thus saving both time and money when it comes to redeployment.
As part of the subject invention, the towline is not itself initially winched but rather is lassoed, with the lasso being winched in. In one embodiment, the lasso is within an annular ridge on a frame through which the towlines pass as they pay out.
Since the towline is taut between its point of anchor to the canister and the decoy, the lasso collapses down around the towline and causes a loop to be formed in the towline. This loop is then dragged to a motor-driven spindle, which when activated causes both the lasso and the looped portion of the towline to wrap around the spindle. When a sufficient number of turns of the looped towline are wrapped around the spindle, the portion of the towline anchored to the canister is cut and the friction of the already wrapped towline is sufficient to draw in the decoy until such time that it is snugged up to the now-deployed cradle. This means that the decoy can be rapidly deployed from a fixed spindle on which the towing line is carried without having to have the spindle also function as a winch which would limit the speed of deployment.
The result is that a compact deployment and retrieval canister {fraction (1/10)}th the size of the aforementioned pods can be utilized so that the decoys need not be sacrificed. Moreover, because of the compact size of the deployment canister, the canisters can be affixed to the aircraft at points which do not interfere with the placement of weapons loads. The result is that decoys can be stored, launched and retrieved without diminishing the weapons payload of the aircraft.
In summary, recovery of a towed body, in one embodiment in the form of a decoy which is initially stowed in a receptacle or canister and which is allowed to pay out behind an aircraft on a towing cable wrapped around a spindle, is accomplished by snaring or lassoing a portion of the towing cable and by dragging it to a further spindle which is driven so as to cause the lasso and a portion of the towing cable to wind up around the driven spindle. When a sufficient amount of the cable is wound around the driven spindle, the cable end secured to the canister is severed to allow all of the rest of the towing cable to be wound up. In one embodiment, a telescoping saddle or docking cradle is provided which extends from the canister to receive the retracted towed body so that it may be secured to the moving vehicle from whence it can be recovered, refurbished and redeployed.